This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A212269 #34 Dec 15 2024 04:36:45 %S A212269 2,5,19,205,3011,92875,4763459,459630701,78223965193,24270274906085, %T A212269 13497818986883771,13571363009654254429,24562890586806439035377, %U A212269 80199120146273882569630015,471874707649862024071657639861,5005895207027974222377733802848093 %N A212269 Number of ways to place k non-attacking kings on an n X n cylindrical chessboard, summed over all k >= 0. %D A212269 Steven R. Finch, Mathematical Constants, Cambridge, 2003, p. 343. %H A212269 Vaclav Kotesovec, <a href="/A212269/b212269.txt">Table of n, a(n) for n = 1..27</a> %H A212269 Vaclav Kotesovec, <a href="https://oeis.org/wiki/User:Vaclav_Kotesovec">Non-attacking chess pieces</a>, 6ed, 2013, p.165 %F A212269 Limit n ->infinity (a(n))^(1/n^2) = 1.342643951124... (see A247413). %Y A212269 Cf. A063443 (n+1), A067958, A194650-A194654, A182407, A247413, A212269. %K A212269 nonn,hard %O A212269 1,1 %A A212269 _Vaclav Kotesovec_, May 12 2012